authorids: models addition
authorids: models addition

* Adds models for aidDENSEINDEX and aidINVERTEDLISTS tables.
  (addresses #1790)

* Refactors the indentations.

Signed-off-by: Mateusz Susik <757e30218753fa054d443840a8ed04de2f7682ac@gmail.com>
Reviewed-by: Esteban J. G. Gabancho <03cb568148df368b792a31d9c4d06b12dc802700@gmail.com>

tiborsimko/invenio,inveniosoftware/invenio,inveniosoftware/invenio,tiborsimko/invenio